The Chilean and Argentine Andes: One Border, Two Climates

Stretching like a mighty spine along the western edge of South America, the Andes Mountain Range stands as a towering testament to nature's grandeur and complexity. This colossal cordillera, spanning seven countries and over 7,000 km (4,350 mi), encompasses some of the planet's most extreme and diverse landscapes. At its heart lies the Chilean and Argentine Andes, where the border between these two nations runs for roughly 5,300 km (3,300 mi)—the longest international mountain border in the world—defined by soaring peaks, glacial valleys, and landscapes that shift from arid desolation in the north to lush, glaciated splendor in the south.

The Dry Andes: A Realm of Arid Majesty

Extending from the Atacama Desert in northern Chile and northwest Argentina, the Dry Andes stretch southward to roughly 35°S in Chile and 40°S in Argentina. This subregion is characterized by a semiarid climate in which precipitation generally increases with elevation, yet the towering peaks and valleys remain remarkably arid year-round.

Despite the scarcity of moisture, the Dry Andes hold some of the highest mountains in the Western Hemisphere, led by Aconcagua, the highest peak in the Americas at 6,961 m (22,838 ft), and Ojos del Salado, at 6,893 m (22,615 ft), the highest volcano on Earth. Nearby, Cerro Bonete (6,759 m / 22,175 ft), Pissis (6,795 m / 22,293 ft), Mercedario (6,720 m / 22,047 ft), and Nevado Tres Cruces (6,748 m / 22,139 ft) round out a cluster of summits among the highest outside the Himalaya, their rugged slopes a testament to millions of years of wind and glacial erosion. Further north, along the Chile-Argentina-Bolivia border zone, a chain of high volcanic peaks including Llullaillaco (6,739 m / 22,110 ft), Incahuasi (6,620 m / 21,719 ft), Tupungato (6,570 m / 21,555 ft), and Socompa (6,051 m / 19,852 ft) marks the northern edge of the Dry Andes, this same high, arid zone forming the southern reach of the lithium triangle whose salt flats extend north into Bolivia and Chile's own Salar de Atacama.

While the Dry Andes may seem bleak at first glance, life persists here. In the valley bottoms, dwarf scrub clings to the parched earth, while small glaciers—modest compared to their counterparts further south, but shrinking rapidly nonetheless—offer a glimpse of the range's glacial past. The Plomo and Horcones glaciers near Aconcagua, for instance, are enduring but diminished remnants of ice that extended over ten times their current length during the last glacial period, and their continued retreat mirrors the broader pattern of glacial loss now documented across the Andes from Venezuela to Tierra del Fuego.

The Wet Andes: Where the Range Turns to Ice

South of roughly 35°S in Chile and 40°S in Argentina, the character of the range changes abruptly. Moisture-laden westerly winds off the Pacific collide with the mountains here rather than being blocked by them, and the Andes transition into the Wet Andes—a realm of ice fields, temperate rainforest, and glacially carved fjords entirely unlike the arid peaks further north. This southern stretch of the range divides further into the Patagonian Andes, running from roughly 40°S to the Strait of Magellan, and the Fuegian Andes, its southernmost continuation across Tierra del Fuego.

The Wet Andes hold the largest concentration of ice outside the polar regions, feeding iconic landscapes including Cerro Fitz Roy and Torres del Paine, both carved from the granite of the Patagonian Batholith into some of the most sought-after climbing objectives on Earth. Given the scale and complexity of this glaciated southern region, we cover its geology, ice fields, climate, and mountaineering history in detail in a dedicated article, The Patagonian and Fuegian Andes; its human and economic geography, meanwhile, is covered in our Chilean Patagonia and Argentine Patagonia articles.

Map of the climatic regions of the Andes: Dry Andes in yellow, Wet Andes in blue, and Tropical Andes in green.

Notable Peaks Along the Border

Beyond the giants of the Dry Andes already described, the Chilean and Argentine Andes hold dozens of other notable summits. Along the border itself, Cerro Escorial (5,447 m / 17,871 ft), Cerro Bayo (5,401 m / 17,720 ft), Cordón del Azufre (5,463 m / 17,923 ft), Falso Azufre (5,890 m / 19,324 ft), Lastarria (5,697 m / 18,691 ft), Nacimiento (6,492 m / 21,299 ft), Olca (5,407 m / 17,740 ft), and the Sierra Nevada de Lagunas Bravas (6,127 m / 20,102 ft) form a dense cluster of high volcanic terrain north of Aconcagua. Nearer Santiago, Maipo rises to 5,264 m (17,270 ft), a popular andinismo objective within easy reach of the Chilean capital.

Further south, within the Wet Andes, Tronador (3,491 m / 11,453 ft) straddles the border near Bariloche, its name—Spanish for "thunderer"—earned from the sound of ice calving from its glaciers, while Volcán Hudson, in Chilean Patagonia, remains one of the region's most active volcanoes, having produced one of the 20th century's largest eruptions in 1991. In the Fuegian Andes at the continent's southern tip, peaks such as Monte Darwin (approximately 2,500 m / 8,202 ft) in the Cordillera Darwin rise directly from fjords and glaciers at the very edge of the inhabited world.

Conclusion

The Chilean and Argentine Andes exemplify the incredible diversity and extremes that can coexist within a single mountain range and a single shared border. From the arid majesty of the Dry Andes, where towering volcanic peaks rise amid semiarid valleys and shrinking glaciers, to the glacial splendor of the Wet Andes further south, this stretch of the Andes showcases the full range of environments a single cordillera can hold. Whether scaling the heights of Aconcagua, trekking through the glacial valleys of Torres del Paine, or tracing the volcanic chain that runs the length of the lithium triangle, the Chilean and Argentine Andes illustrate the power and diversity of the Andes at their most extreme.